Make sure to have your BF wear protection!!!!!!!!!!!!!
It really depends on the woman whether or not there is a lot of bleeding. Tampons, bike riding, horseback riding, etc. can all break the hymen making it so during that woman's first sexual encounter- there is no blood. However, some other women experience a LOT of blood and pain, it's kind of hard to tell before hand what will happen.
If you don't usually use tampons, do a lot of riding, masturbate or have been fingered you may experience bleeding. If you really want to avoid that you can get a small toy from a sex shop (make sure it's narrow, because if you aren't experienced a big one can HURT). The person working there can help you figure out what's good to start with, but keep in mind you get what you pay for. Cheap (50 and under) usually suck and break easier. If you don't feel comfortable doing, don't have the money, or are under 18 just experiment with yourself to try and break the hymen.